Silver halide emulsion containing aromatic azocarbonamide antifog agent

ABSTRACT

Aromatic azocarbonamides act as antifogging agents when included in silver halide photographic emulsions without seriously affecting film speed, contrast or maximum densities.

United States Ferguson a atent [1 1 1 Aug. 19, 1975 1 SILVER HALHDE EMULSION CONTAINING AROMATIC AZOCARBONAMIDE ANTIFOG AGENT [75] Inventor: Alan Norman Ferguson, Harlow,

England [73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn.

[22] Filed: Oct. 2, 1972 [2]] Appl. No.1 293,772

[30] Foreign Application Priority Data Oct. 18, 1971 United Kingdom 47056/71 [52] US. Cl 96/76 R; 96/109; 260/192;

260/553; 96/665 511 Int. Cl. G03C 1/48; 603C 1/34 [58] Field of Search .6 96/109, 66.5, 76 R [56] References Cited UNITED STATES PATENTS 3,655,391 4/1972 Merli et a1. 3,732,104 5/1973 Vandenabeele et a1. 96/109 Primary Examiner-Won H. Louie, Jr. Attorney, Agent, or F irmAlexander, Sell, Steldt & DeLaHunt 10 Claims, N0 Drawings SILVER HALIDE EMULSION CONTAINING AROMATIC AZOCARBONAMIDE ANTIFOG AGENT This invention relates to photographic silver halide emulsions containing organic anti-fogging agents and to ring-substituted azocarbonamides for use as antifogging agents for photographic silver halide emulsions.

According to the invention there is provided a photographic silver halide emulsion which has in fog inhibiting reactive association therewith an azocarbonamide.

We find that these azocarbonamides act as antifogging agents for photographic emulsions. It is believed that the desired anti-fogging effect is achieved because the azocarbonamide acts as an oxidizing agent for those silver halide crystals or grains in the emulsion which become accidentally developable, i.e., fogged, during production or handling of the emulsion, e.g., by accidental slight light exposure, chemical action or strain. Thus when a crystal or grain becomes fogged, it is oxidized by the azoearbonamide and so the crystal or grain does not therefore become developed as a fog speck when the emulsion is developed after normal light exposure.

The azocarbonamide is preferably added to the pho tographic emulsion. It can instead be present in a layer adjacent to an emulsion layer.

The optimum amount of azocarbonamide to be added to a photographic emulsion to give the desired anti-fogging effect can easily be found by simple experiment. In general, however, good results will be given when from 0.025 to 1.0 millimole of an azocarbonamide, and preferably a ring-substituted azocarbonamide, is added per mole of silver in the emulsion. When added in these amounts, the azocarbonamide does not seriously effect the other desirable properties of the emulsion such as film speed, and in addition we find that the azocarbonamide has comparable or better anti-fogging properties and also comparable or better gamma (contrast) and D-max when added to photographic emulsions as compared with azodicarbonamide. Also it is often possible to add less of the azocarbonamide, and particularly a ring-substituted aZocarbonamide, than azodicarbonamide to achieve comparable anti-fogging properties.

It is believed that these azocarbonamides act as antifogging agents for photographic emulsions because they can be readily reduced, i.e., they are oxidizing agents, and they oxidize developable silver halide specks to a non-developable form. This oxidation is illustrated for example, by the following reaction using phenylazocarbonamide:

Certain of the azocarbonamides of this invention, and particularly ring-substituted azocarbonamides, are unstable when in contact with the emulsion, e.g., hy drolytically unstable, and are decomposable in a rea sonable time at normal temperatures, e.g., days at 60F, to innocuous decomposition products. Therefore these azocarbonamides can be added to photographic silver halide emulsions in relatively large amounts, i.e., in an amount which is at least sufficient to oxidize the silver in those silver halide crystals or grains which would otherwise become developable after the emulsion has been prepared and coated on a suitable substrate and dried, any excess azocarbonamide being capable of decomposing in a reasonable time at normal temperatures to leave insufficient azocarbonamide to interfere substantially with image exposure and development of the emulsion coating.

Therefore certain azocarbonamides and preferably ring-substituted azocarbonamides can be used as the oxidizing agent required to eliminate undesirable fog in photographic elements according to the inventions described in our copending US. patent application Ser. Nos. 243,463 and 244,276, filed Apr. 12, 1972 and Apr. 14, 1972 respectively. They are added to the emulsion in relatively large amounts, e.g., from 1.5 to 25 millimoles per mole of silver :in the emulsion and initially they almost completely desensitize the emulsion to light. However, they decompose in a reasonable time so that they protect the emulsion from fog formation during manufacture and coating of the emulsion and handling of the coated emulsion, and then the emulsion regains its speed before use.

The photographic emulsion to which the azocarbona mides can be added can be one which is suitable for black and white or for color photography, or for use in radiography. Also the emulsion can be a negative emulsion or a direct positive emulsion. Further the silver halide can be the bromide, iodide, a mixed halide or any of the silver halide materials useful in photographic techniques.

The preferred azocarbonamides used in photographic emulsion according to the invention are aryl azocarbonamides, preferably ring-substituted azocarbonamides represented by the formula:

Ar N N R wherein Ar represents any aromatic group and R represents a carbonamide. According to one aspect of the invention there is provided an novel azocarbonamide represented by the formula:

wherein Ar represents any aromatic group and R represents a carbonamide with the exception of the case where both Ar represents a phenyl group and R represents the group CON H The preferred carbonamide groups may be further characterized as in which R and R which may be the same or different, each represents a hydrogen atom, an alkyl, alkylene, alicyclic, aryl, aralkyl, alkaryl group or a grouping containing a center of positive charge and having associated with it one or more negatively charged moieties sufficient to impart electrical neutrality, or R and R together with the nitrogen atom to which they are linked represent the atoms required to complete a bet erocyclic ring which may itself be substituted or contain a center of positive charge having associated with it one or more negatively charged moieties sufficient to impart electrical neutrality, with the exception of the 5 case where Ar represents a phenyl group and R and R both represent hydrogen atoms. Those compounds which are suitable for use according to the invention described in our above noted copending US. patent applications oxidizing agents having an oxidizing potential of from 0.08 to +0.50. These compounds are hydrolytically unstable in that they decompose when in contact with an emulsion within about 60 days at 60F. Illustrative of the types of groups which can be used for the aromatic group Ar are, for example, an aryl, aralkyl or alkaryl group such as a phenyl, naphthyl, or substituted phenyl group of the general formula:

or a heterocyclic group which can contain a quaternizable nitrogen atom such as one of the groups having the general formula:

in which the groupings represented by R may be different from one another and are a hydrogen or halogen atom or an alkyl, alkylene, alicyclic, aryl, aralkyl, alkaryl, COOH, SO H, alkyl ammonium of fiuoroalkyl group.

The most preferred class of azocarbonamides which ace particularly well as excellent anti-fogging agents are those where Ar represents a phenyl or a naphthyl group. These may be substituted phenyl or naphthyl groups as well as unsubstituted. Also hetero-cyclic groups as set out above and R and R represent hydrogen atoms or lower alkyl groups, e.g., containing 1 to 4 carbon atoms may be used. In order to improve the water solubility of such compounds the grouping Ar may contain one or more water-solubilizing groups such as -COOH or -SO H. Substituents such as I JO tend to desensitize photographic emulsions and so are preferably not present.

These azocarbonamides are relatively hydrolytically stable and so will generally be added in quite small amounts as noted above to photographic emulsions to act as anti-fogging agents. Generally the water solubility of these compounds is sufficient to enable them to be added in these relatively small amounts in aqueous solution which has the advantage of being compatible with the emuision and relatively inert to the emulsion.

When the azocarbonamides contain groupings hav ing centers of positive charge, e.g., quaternary ammonium groupings, they can have the general formula:

or more particularly in which R represents a carbonamide wherein a substit uent in the nitrogen atom of the carbonamide group contains at least one quaternary ammonium, R represents a grouping containing at least one quaternary ammonium grouping, R represents a hydrogen atom or an aliphatic, alicyclic, aromatic or heterocyclic group, or R and it? together with the amide nitrogen atom cornwhile an example of a suitable grouping represented by R and R together with the amide nitrogen is where R represents a lower alkyl group.

The negatively charged moiety or moieties can be one or more separate anions associated with the amcarbonamide or the azocarbonamide can also contain one or more negatively charged substituents as part of its structure. In the case where the azocarbonamide has associated with it one or more separate anions, suitable anions include, for example, aryl sulphonates such as toluene-p-sulphonate, alkyl sulphites, boron tetrafluoride (BFf), iodide, iodate, chloride, chlorate, per chlorate and nitrate ions. On the other hand where the negatively charged moiety forms part of the azocarbonamide, the negatively charged grouping can include, for example, a sulphobetain grouping.

These charged azocarbonamides are readily soluble in water and so they can readily be incorporated into photographic emulsions without the use of organic solvents which, besides being expensive, may have undesirable side effects upon the emulsion. Also their good solubility enables them to be distributed throughout the emulsion very uniformly. Further their ready water solubility enables one to incorporate relatively large amounts of them into the emulsion asrequired according to our copending US. patent application Ser. Nos. 243,463 and 244,276.

Many of the ring-substituted az ocarbonamides of the invention can be prepared by oxidizing (e.g., with acid ified potassium permanganate), the corresponding ring-substituted hydrazocarbonamide. Depending upon the particular ringsubstituted azocarbonamide, this intermediate hydrazocarbonamide can be prepared in a number of ways.

Thus a phenylazocarbonamide, substituted or unsubstituted on the phenyl ring and unsubstituted on the amide nitrogen atom, can be prepared by reacting the corresponding phenylhydrazine, preferably as its hydrochloride salt, with a cyanate, e,g., KCNO, and then oxidizing the resulting phenyl hydrazocarbonamide. This reaction is illustrated by the following scheme for preparing N-p-ethylphenylazocarbonamide:

6 NHNH .CI-Il -l- KCNO CCNH lldtGONll oxidation C H C H A phenylazocarbonamide substituted or unsubstituted on the phenyl ring and monosubstituted on the amide nitrogen atom can be prepared by reacting the corresponding phenylhydrazine with the appropriate isocyanate followed by oxidation of this intermediate hydrazocarbonamide. This reaction is illustrated by the following scheme for preparing N- ethylphenylazocarbonamide:

NHNH

C l-I NCO 3 N'HNHC ONHC 2 H N.-NC ONHC H I a n A phenylazocarbonamide substituted or unsubsti tuted on the phenyl ring and di-substituted on the amide nitrogen atom can be prepared by reacting the corresponding phenylhydrazine with the appropriate di-substituted carbamyl chloride, e.g., a dialkyl chloride, followed by oxidation of the resulting intermediate hydrazocarbonamide. This reaction is illustrated by the following scheme for preparing N-dimethylphenylazocarbonamide:

NHNH2 NHNHCON(CH3)2 N=NCON(CH3)2 A heterocyclic azocarbonamide unsubstituted on the amide nitrogen atom can be prepared by reacting the corresponding heterocyclic hydrazine, preferably in the form ofa salt with a cyanate, e.g., KCNO, and then oxidizing the resulting heterocyclic hydrazocarbonamide. This reaction can be illustrated by the following scheme for preparing 2-quinolineazocarbonamide:

KCNO b HEHCl NHNHCONH oxidation Another route for the preparation of the ring- Azocarbonamides containing a quaternary ammosubstituted azocarbonamides is to react the correnium group can be prepared from azocarbonamides sponding azo ester with a diamine. This route is particularly useful for the preparation of azocarbonamides which have tertiary amine substituents.

Thus a heterocyclic azocarbonamide which is monoor disubstituted on th amide nitrogen atom can, for example, be prepared by making the corresponding heterocyclic hydrazoester, oxidizing this to the azo ester followed by reaction with a diamine. This diamine may form with the azo ester an azocarbonamide in which the amine nitrogen atom forms part of a heterocyclic ring containing a second tertiary nitrogen atom or an azocarbonamide in which one substituent on the amine nitrogen atom contains a tertiary nitrogen atom. The following reaction scheme illustrates this procedure:

substituted on the amide nitrogen atom with a grouping containing a tertiary nitrogen atom by reacting with a quaternizing agent such as p-toluene sulphonate or ethyl iodide.

The invention will now be illustrated, by way of example, with reference to the following preparation of phenylazocarbonamide, Examples 1 to 33 illustrating the preparation of other azocarbonamides, and Examples 34 to 36 illustrating the use of azocarbonamides in photographic silver halide emulsions.

PREPARATION Phenylazocarbonamide Potassium cyanate (16.2 g, 0.2M) in water ml) c NHNHCOOC2H5 Also phenylazocarbonamides substituted or unsubstituted on the phenyl ring and monoor disubstituted on the amide nitrogen atom in which one or both substituents on the amide nitrogen atom contain a tertiary nitrogen atom or the amide nitrogen atom forms part of a heterocyclic ring containing a second tertiary nitrogen atom can be made in a similar fashion to the above heterocyclic azocarbonamides. This can be illustrated by the following reaction scheme:

NHNHOOOC H tion of l-phenylsemicarbazide (10.0 g, 0.066 M) in water (200 ml), at 80C.

The hot solution was then filtered. On cooling phenylazocarhonamide crystallized out as golden plates. The product was filtered off and dried under vacuum. The yield was 7.0 g (melting point 1 14C).

A sample for analysis was recrystallized from carbon tetrachloride.

Analysis: C H N O requires: C 56.4%; H 4.7%; N 28.2%; found: C 56.1%; H 4.6%; N 27.7%.

EXAMPLE 1 N-Ethylphenylazocarbonamide Phenylhydrazine (21.6 g, 0.2M) was dissolved in benzene (25 ml) and added dropwise, with stirring, to a solution of ethylisocyanate 14.3 g, 0.2M) in benzene (25 ml). After addition was complete the reaction mixture was refluxed for /2 hour. On cooling, a white crystalline precipitate of the 1-phenyl-4-ethyl semicarbazide was formed. Filtering, washing with cold water and vacuum drying gave 30 g of the intermediate.

l-Phenyl-4-ethylsemicarbazide l 1.8 g, 0066M) was oxidized as described in the preparation to give a yellow crystalline solid which was recrystallized from cyclohexane/ethyl acetate mixture to give 5.2 g of the desired product (melting point 55-56C).

Analysis: C H N O requires: C 61.1%; H 6.2%; N 23.8%; found: C 61.1%; H 6.2%; N 23.1%.

EXAMPLE 2 N-Dimethylphenylazocarbonamide Dimethylcarbonoylchloride (21.5 g, 0.2M) was added slowly with stirring to an icecooled solution of phenylhydrazine (21.6 g, 0.2M) in pyridine (125 ml). After addition was complete, stirring was continued for 2 hours at 20C. The reaction mixture was then poured into 500 ml. of ice-water. The cream colored solid pre cipitate was filtered off, washed with cold water and dried at 60C. The yield of 4,4-dimethyl-1- phenylsemicarbazide was 12.3 g (melting point 160C).

4.4-Dimethylsemicarbazide (1 1.8 g, 0066M) was dissolved in 600 ml of water at 80C and oxidized as described in the preparation to give an orange solid product which was recrystallized from ethanol. The yield was 3.0 g (melting point 73C).

Analysis: C H N O requires: C 61.0%; 1-1 6.2%; N 23.75%; found: C 61.4%; H 6.0%; N 24.0%.

EXAMPLE 3 p-Fluorophenylazocarbonamide Potassium cyanate (12.6 g, 0. 155M) in water (50 ml) was added with stirring to a solution of 4-fluorophenylhydrazine hydrochloride (25.0 g, 0154M) in water (300 ml) at room temperature. The heavy precipitate of 1-(pfluorophenyl)semicarbazide which quickly came down was filtered off, washed with cold water and vacuum dried. The yield was 30.0 g (melting point 202--2()3C J.

l-(p-Fluorophenyl)semicarbazide (11.2 g, ().066M) was dissolved in 350 ml of boiling water and oxidized as described in the preparation. to give a yellow solid product which was recrystallized from benzene. The yield was 6.7 g (melting point 138C).

Analysis: C H N OF requires: C 50.3%; H 3.6%; N 25.2%; found: C 50.4%, H 3.6 /1; N 24.7%.

EXAMPLE 4 oTolylazocarbonamide Potassium cyanate 13.0 g, 0158M) in water (50 ml) was added with stirring to a solution of o-tolylhydrazine hydrochloride (25.0 g, 0158M) in water (200 ml) at room temperature. The heavy white precipitate of 1(0- tolyl)semicarbazide which quickly came down was filtered off, washed with cold water and vacuum dried. The yield was 27.5 g (melting point 1634C).

1-(o-Tolyl)s,ernicarbazide (11.0 g, 0066M) was dissolved in 200 ml of boiling water and oxidized as described in the preparation, to give a pale yellow solid which was recrystallized from benzene to give 9.2 g of yellow crystals (melting point 1 15C).

Analysis: C H N O requires: C 58.9%; H 5.5%; N 25.8% found: C 59.1%; H 5.3%; N 25.4%.

EXAMPLE 5 2-Quinolylazo[N-( 4-methy1 piperazine)amide] Ethylcarbazate (16.6 g, 0.16M) in ethanol (30 ml) was added to a solution of 2-chloroquinoline (26.0 g, 0.16M) in ethanol ml) containing concentrated hydrochloric acid 10 ml). The reaction mixture was then refluxed for 3 hours, cooled and neutralized with dilute ammonia solution. The white solid precipitate formed was filtered off and recrystallized from ethanol to give 23.5 g of white crystals of ethyl-2-quinolylhydrazocarboxylate (melting point 1678C).

l-Chlorobenzotriazole (7.83 g, 0.05M) was dissolved in methylene dichloride ml) and added dropwise to a stirred solution of ethyl-2-quinolylhydrazocarboxylate (1 1.6 g, 0.05M) in methylene dichloride (150 ml). lce cooling was used to keep the temperature below 20C during the addition. The reaction mixture was then stirred for 1 hour at room temperature, filtered and the filtrate washed with 2 Normal NaOH (25 ml), then water (25 m1) and finally dried over sodium sulphate. Evaporation of the methylene dichloride gave ethyl-2-quinolylazocarboxylate: as a dark orange solid (melting point 57C).

Ethyl 2-quinolylazocarboxylate (4.6 g, 0.02M) was dissolved in ether (50 ml) and stirred while N-methyl= piperazine (2.2 g, 0022M) was slowly added. The rC action mixture was stirred over-night at room temperature then the precipitate formed was filtered off and recrystallized from cyclohexane to give 4.0 g of orangered needles of 2-quinolylazo[ T 1-( 4- methylpiperazine)arnidel (melting point 118C).

Analysis: C H N O requires: C 63.6%; H 6.0%; N 24.8%; found: C 63.3%; H 6.0%; N 24.7%.

EXAMPLE 6 2-Quinolylazocarbon-( N-piperidino )amicle Piperidine (2.12 g, 0.025M) in ether (20 ml) was added dropwise to a stirred solution of ethyl-2- quinolylazocarboxylate (5.7 g, 0025M) in ether (200 ml). The reaction was stirred for 1 hour at room tern perature and the orange solid precipitate was filtered off. Recrystallization from 100 petroleum ether gave 4.3 g of an orange solid (melting point l278C).

Analysis: C H N O requires: C 67.2%; H 6.0%; N 20.9%;found: c 67.0%; H 5.91%; N 20.9%.

3 ,900,321 1 1 l2 EXAMPLE 7 Example 7 and quaternizing the appropriate azodicarbonamide having a tertiary amino substituent with the p-nitro-phenylazocarbon(N-(4-ethyl-4-methylappropriate quaternizing agent as shown in the followpiperazinium))amide iodide ing Table I.

Table 1 Example Formula Solvent for re- Analysis No. crystallization (X Q. N NCONHCH2 CMHLHNSOHS requires 1 (9 not recrystallized Q 535, H 4.5, I 8 N 14 9; S (x8;

CH N02 3 found:

a ri q a C 52.0; H 4 4 N N=NCON CHHHNSOI requires L C 46.5; H 5.0-, 9 2 N 16.0; I 29.0;

ethanol found: I- C li CH C 46.1; H 5.0; N 15.8;1285.

p-nitrophenylazocarbon N-(4-methylpip erazine)- EXAMPLES 10 to 18 amide (2.0 g) was dissolved in ethyl iodide (20 ml) at room temperature and allowed to stand overnight. The orange-yellow solid product was filtered off, washed with ether and dried under vacuum. The yield was 2.3

The following general reaction was used.

Potassium cyanate (l6.2 g; 0.2 M) in water (50 ml) was added with stirring to a solution of the arylhydra- Zine hydrochloride (0.2 M) in water (100 ml) at room temperature. Almost immediately, a heavy white pre- Structural formula:

clpitate of l-arylsemlcarbazide came down. The pre- CH cipitate was filtered 0H, washed with a little cold water 3 and dried. Q N- N NCON @N I A solution of potassium permanganate (7.0 g), dilute sulphuric acid ml, 1 N) and water ml) was C l-l2 40 heated to C and slowly added, with stirring, to a solution of the l-arylsemicarbazide (0.066 M) in water Analysis: m zo sQ-a requires: C H N (200 ml) at C. The hot solution was then filtered. fOUI'IdI C 389%; H N 15.4%. The arylazocarbonamide which crystallized on cooling EXAMPLES 8 and 9 was filtered off and dried under vacuum. Recrystallizatlon gave pure products. Other azocarbonamides containing centers of posi- 45 The compounds prepared and their properties are tive charge were prepared following the procedure of listed in the following Table ll.

Table 11 -Continue .l

N-NCONH Example Melting lization Solvent for Analysis point reerystal- ("/i 12 R 3-Cl 121 ethanol/ water requires:

C 45.8; H 3.3; N 22.9;

found:

C 44.6; H 3.2; N 22.3;

13 R 4Cl 188 benzene R requires:

C 45.8; H 3.3; N 22.9; found: C 45.8; H 3.4; N 22.3;

14 R 2C1 161 ethanol/ water requires:

C 38.6; H 2.3; N 19.3; found:

C 38.0; H 2.4; N 18.9;

ethanol/ 15 R 3Br 138 water 1:5

R H requires:

found: C 36.6; H 2.6; N 17.9;

16 R 2F 131 ethanol/ water 1:1

requires:

C 50.3; H 3.6; N 25.2; found:

C 50.3; H 3.6; N 25.1;

17 R 3F 112 ethanol/ water 1:5

requires:

C 50.3; H 3.6; N 25.2; found:

18 R 4-COOH 205 acetic acid R H requires:

C 49.8; H 3.6; N 218;

found:

C 48.6; H 3.9; N 20.0;

EXAMPLE 19 p-Sulphophenylazocarbonamide p'SulphophenylhydraZine (37.6 g; 0.2 M) was suspended in water (150 ml) and stirred while a solution of potassium cyanate (16.2 g; 0.2 M) in water (50 ml) was added. The reaction warmed spontaneously and a clear solution was obtained. After 1 hour concentrated hydrochloric acid was added until no further precipitation occurred then stirring was continued for a further 1 hour. The white solid product was filtered off and dried under vacuum over KOH pellets.

The yield was 39.5 g.

1-p-Sulphophenylsemicarbazide l 1.5 g; 0.05 M) from the above reaction was suspended in acetonitrile (300 ml) and stirred while l-chlorobenzotriazolc 15.4 g; 0.10 M) in acetonitrile (150 ml) was added dropwise. An orange color developed in the reaction mix- EXAMPLES 20 to 23 Phenylsemicarbazide substituted or unsubstituted on the phenyl ring and mono-substituted on the amide nitrogen can be prepared by reaction of the appropriate phenylhydrazine with an isocyanate followed by oxidation of the resulting intermediate substituted phenyl semicarbazide. This is illustrated by the following preparation.

N-Ethyl-phenylazocarbonamide Phenylhydrazine (21.6 g; 0.2 M) was dissolved in benzene ml) and added dropwise, with stirring, to a solution of ethyl isocyanate (14.3 g; 0.2 M) in ben zene (25 ml). After addition was complete, the reaction mixture was refluxed for minutes. On cooling, a white crystalline precipitate of l-phenyl-4-ethyl semicarbazide was formed. Filtering, washing with cold water and drying gave 30 g of the intermediate.

1-Phenyl-4-ethyl semicarbazide l 1.8 g; 0.06 M) was oxidized as described in Examples 10 to 18 to give a yellow crystalline solid which was recrystallized from cyclohexane/ethyl acetate to give 5.1 g of yellow plates.

Other phenylazocarbonamides were prepared in a similar fashion and their properties are listed in the following Table 111.

Table 111 orange solid product which was recrystallized from ethanol. The yield was 3.0 g (melting point 73C).

Analysis: C,,H N;,O requires: C 61.0%; H 6.2%; N 23.8%; found: C 61.4%; H 6.0%; N 24.0%.

EXAMPLES 26 to 29 Phenylazoearbonamides substituted on the amide nitrogen with a tertiary amine moiety available for quaternization to prepare the quaternary ammonium salt compounds shown, for example, in Examples 7 to Solvent for reerystallization Analysis requires:

cyclohexane/ C H N O C 61.1; H 6.2; N 28.8; found:

C 61.1; H 6.2; N 28.2;

found: C 48.3; H 4.3; N 25.0;

cyclohexanc C m a requires:

C 70.3; H 5.4; N 17.6; found:

C 69.1; H 6.1; N 17.4;

requires:

ethylacetate C ,-,H N 0 found: C 64.4; H 3.7; N 17.5.

EXAMPLE 24 N,N-Dimethyl-phenylazocarbonamide Dimethylcarbamyl chloride (21.5 g; 0.2 M) was added slowly, with stirring, to an ice-cooled solution of phenyl hydrazine (21.6 g; 0.2M) in pyridine (125 ml). After addition was complete, stirring was continued for 2 hours at 20C. The reaction mixture was then poured into 500 ml of ice-water. The cream colored solid precipitate was filtered off, washed with cold water and dried in air at 60C. The yield of 4,4-dimethyl-lphenylsemicarbazide was 12.3 g (melting point 160C).

4,4-Dimethyl-l-phenylsemicarbazide 1 1.8 g; 0066M) was dissolved in 600 ml of water at 90C and oxidized as described in Examples 10 to 18 to give an 9, can be prepared by preparing the appropriate azoester and then reacting this with the appropriate diamine. This is illustrated by the following preparation.

p-Nitrophenylazo-( N'( 4-pyridy1methyl )amide) To a solution of the above hydrazo compound (22.5 g; 0.10 M) in methylene dichloride 100 ml) was added dropwise. with stirring, a solution of lchlorobenzotriazole (15.4 g; 0.10 M) in methylene dichloride (50 ml). The reaction mixture was stirred for 1 hour at room temperature and the benzotriazole hy drochloride formed was filtered off. The filtrate was evaporated to give 18.6 g of ethyl-pnitrophenylazocarboxylate as a golden brown solid.

The azocarboxylate (8.8 g; 0.04 M) was dissolved in ether (50 ml) and stirred while a solution of 4- aminomethylpyridine (4.4g; 0.04 M) in ether (15 ml) was run in slowly. An orange-red precipitate was quickly formed. Stirring was continued for 1 hour, then ride and stirred while a solution of l-chlorobenzotriazole 15.4 g; 0.10 M) in methylene dichloride 100 ml) was added dropwise. External ice-cooling was used to keep the temperature below 20C during the addition. After addition was complete, a further 2 hours stirring at room temperature was given, then the reaction mixture was filtered.

The filtrate was washed with 2 Normal NaOH (50 ml), followed by water (50 ml) and dried over Na SO.,. Evaporation of the filtrate gave 5.2 g of an orange-red solid which was recrystallized from ethanol (melting point 16l2C).

Analysis: C H N O requires: C 60.0%; H 4.0%; N 28.0%; found: C 60.0%; H 4.0%; N 27.7%.

the roduct was filtered off and recr stallized from ace y EXAMPLE 31 tonitrlle to give 9.3 g of orange platelets.

Other analogous azocarbonamides were prepared in A coarse-grain gelatine silver bromoiodide emulsion, a similar fashion and their properties are listed in the of cubic habit and having a mean grain size of approxifollowing Table IV. mately 2.0 microns, was prepared by ripening under Table IV Example /R" Melting Solvent for Analysis No. N=NCON\ point recrystal- (70) R (C) lization 26 R=R'=R' =H 120 ethanol C, ,H, N,0

R"=3-CH2 requires: Pyridyl C 65.0; H 5.0;

N 23.4; found: C 65.5; H 5.6; N 23.5;

27 R=4*NO2R=R"=H I80 acetoni- C H N Q,

trile R"=3CH2 requires: Pyridyl C 54.7; H 3.9;

N 24.6; found: C 54.8; H 4.0; N 24.4;

28 R=4N()2R'=R"=H 136 acetoni- C, ,H,,N,,0

trile R" =2 H. requires: Pyridyl C 54.7; H 3.9;

N 24.6 found: C 55.1; H 4.3; N 24.5; 29 R=4-NO2R'=R'=H 172 acetoni C, -,HN,-,O;,

trilc R "'=4CH2 requires: Pyridyl C 54.7, H 3.9;

N 24.6; found: C 54.9; H 3.8; N 24.6.

EXAMPLE ammoniacal conditions, the final emulsion having an 2 QumO1meazocarbonamldc iodide content 0 about 2 moles percent The emulsion was digested with a sulphur and a gold sensitiser. After stabilization by the addition of 4-hydroxy-5-2- hydroxyethyl-o-methyll :3:3a:7-tetraazaindene 3- amino-5-methylthio-1:2:4-triazole salt (see Example 1 of our United Kingdom Pat. No. 1,022,872), the emulsion was divided into four parts. To one part (Emulsion A) no addition was made while to the second part (Emulsion B) an aqueous solution of azodicarbonamide was added, to the third part (Emulsion C) an aqueous solution of m-bromo-phenylazocarbonamide was added, and to the fourth part (Emulsion D) an aqueous solution of m-chlorophenylazocarbonamide was added. After the addition of necessary coating aids, the emulsions were coated on polyester bases to give a silver coating weight of 5.0 g/meter? Each emulsion layer was then coated with a protective gelatin super coat containing a gelatin cross-linking agent. The coated films were dried, exposed to a continuous wedge in a sensitometer, and processed at 104F in a standard, commercially-available developer of the type suitable for use in a modern X-ray film processing machine having a total dry-to-dry process time of 90 seconds. The relative fog speeds, fog levels, gamma and D-max were measured and results were as shown in the following Table V.

The amounts of the aqueous solutions added in each case was the optimum amount.

As can be seen from these results, the anti-fogging effects of the ring-substituted azocarbonamides in the emulsions according to the invention (Emulsions C and D) were excellent as compared with the Emulsion A without any addition, and also as good as or better than the anti-fogging effects of azodicarbonamide (Emulsion B), even though much smaller amounts of the ringsubstituted azocarbonamides were added to Emulsions C and D. It will further be noted that the other photographic properties of the emulsions according to the invention were similar to the emulsion without addition (Emulsion A).

EXAMPLE 32 Coarse-grain gelatine or silver bromoiodide emulsions, of cubic habit and having a mean grain size of approximately 2.0 microns, were prepared by ripening under ammoniacal conditions, the final emulsions having iodide contents of about 2 moles percent. The emulsions were digested with a sulphur and gold sensitizer. After stabilization by the addition of 4-hydroxy-5- 2-hydroxyethyl-6-methyl-1:3:3a:7-tetraazaindene 3- amino-5-methylthio-1:2z4-triazole salt, additions of aqueous solutions of various azocarbonamides in various amounts (ml of azocarbonamide per mole of silver in the emulsion) were made as shown in the following Tables V1 to X for comparison purposes, no addition and the addition of an aqueous solution of azodicarbonamide were also made.

After the addition of the necessary coating aids, the emulsions were coated on polyester bases to give a silver coating weight of 5.0 glmeter Each emulsion layer was then coated with a protective gelatin super coat containing a gelatin cross-linking agent. The coated films were then dried, exposed to a continuous wedge in a sensitometer and processed at 104F in a standard, commercially available developer of the type suitable for use in a modern X-ray film processing machine having a total dry-to-dry process time of 90 seconds. The relative log speeds, fog levels, average contrast and D-max were measured and the results are shown in Tables V1 to X.

Table VI Compound Relative added Quantity log (Example added speed Average No.) (mM/M) Fog (0.5) contrast D-max No addition 0.11 1.45 0.55 1.28 Azodicarbonamide 0.625 0.07 1.45 0.65 1.28 0.025 0.10 1.54 0.71 1.38 0.075 0.09 1.45 0.60 1.29 4 0.25 0.08 1.41 0.66 1.29 0.75 0.07 1.29 0.70 1.30 2.50 0.07 1.21 0.80 1.33 0.025 0.10 1.50 0.60 1.28 0.075 0.10 1.52 0.50 1.26 3 0.25 0.08 1.41 0.67 1.26 0.75 0.08 1.34 0.82 1.32 2.50 0.07 1.20 0.97 1.35 0.025 0.08 1.45 0.65 1.28 0.075 0.09 1.46 0.72 1.38 l 1 0.25 0.07 1.44 0.90 1.40 0.75 0.07 1.21 0.74 1.30 2.50 0.07 1.04 0.80 1.25

Table V11 Compound Relative added Quantity log (Example added speed Average No.) (mM/M) Fog (0.5) contrast D-max No addition 0.10 1.53 0.86 1.42 Azodicarbom amide 0.625 0.08 1.48 0.50 1.26 0.025 0.10 1.44 0.81 1.30 0.075 0.1 l 1.42 1.20 20 0.25 0.09 1.54 0.80 1.34 0.75 0.08 1.48 0.78 1.32 2.50 0.08 1.37 0.75 1.34 0.025 0.09 1.55 0.91 1.40 0.075 0.08 1.42 0.65 1.28 23 0.25 0.08 1.42 0.96 1.43 0.75 0.08 1.47 0.65 1.32 2.50 0.08 1.28 0.60 1.20

Table V111 Compound Relative added Quantity log (Example added speed Average No.) (mM/M) Fog (0.5) contrast D-max No addition 0.14 1.80 1.74 2.27 Azodicarbonamide 0.625 0.08 1.66 1.61 1.84 0.025 0.08 1.70 1.77 2.17 0.075 0.08 1.57 1.71 2.02 21 0.25 0.08 1.40 1.85 2.14 0.75 0.07 1.06 1.75 1.71 2.50 0.08 0.69 1.79 1.28 0.025 0.10 1.71 1.69 2.04 0.075 0.08 1.75 1.69 2.21 13 0.25 0.07 1.59 1.63 1.75 0.75 0.07 1.42 1.76 1.90 2.50 0.07 1.26 1.57 1.70

Table 1X Compound Relative added Quantity 10g Example added speed Average No.) (mM/M) Fog (0.5) contrast Dmax No addition 0.13 1.71 1.36 1.77 Azodicarhonamide 0.625 0.011 1.66 1.40 1.68 0.025 0.10 1,84 1 51 2.20 0.075 0.11 1.68 1.56 1.93 10 0.25 0.10 1.70 1.72 2.17 0.75 0.09 1.66 1 74 2.15 2.50 0.07 1.45 1 54 1.73

Table X -(ontinued b e X -Cfllinued Compound Relative Compound Relative added Quantity log added Quantity log Example added specd Average 5 (Example added speed Average N0.) (mM/M) Fog (0.5) contrast D-max No.) (mM/M) Fog (0.5) contrast D-max N0 addition 0.08 1.80 1.72 2.05 0.75 0.05 1.68 2.07 2.17 Azodicarbon- 2.50 0.04 1.55 1.93 1.93 am1dc 0.625 0.05 1.73 1.66 1.89 0.025 0.06 1.69 1.51 1.89 0.025 0.05 1.70 1.59 1.92 0.075 0.05 1.63 1.88 2.32 0.075 0.06 1.67 1.69 2.00 25 0.25 0.05 1.38 1.86 2.16 0.25 0.05 1.54 1.81 1,98 0.75 0.05 1.03 2.04 1.91 0.75 0.04 1.35 1.83 1.88 2.50 0.04 0.55 1.63 1.36 2.50 0.04 1.15 1.69 1.70 0.025 0.06 1.69 1.67 1.89 0.075 0.06 1.71 1.65 1.93 17 025 005 L60 178 215 As can be seen from the results, azocarbonamldes :32 15 added to a silver halide emulsion acted as anti-fogging .6 .78 0025 005 L71 L68 Z06 agents but dld not reduce the photographic speed to 0.075 0.04 1.68 1.59 1.83 any marked extent as compared with emulsions to 16 8-82 {-22 5?; which no addition had been made. Also it can be seen that in general the addition of an azocarbonamide gave 9025 173 a reduction in fog of about the same level as that ob- 0.075 0.07 1.74 1.87 2.33 2 025 008 L61 1.85 223 tamed by adding azodlcarbonamide. Further, less am- 0.75 0.04 1.45 1.95 1.99 carbonamide was often required to give comparable 2.50 0.03 1.26 1.79 1.87 0.025 0.09 1.73 1.73 2.09 annfoggmg effects" 0.075 0.06 1.65 1.64 2.05 14 0.25 0.05 1.63 1.73 2.13 EXAMPLE 33 0.75 0.05 1.51 1.78 1.95 L31 In order to test the suitability of some of the azocar- 0.025 0.06 1.76 1.79 2.00 0075 Q06 L75 L77 208 bonamrdes of the invention for use in emulsions as de- 22 .25 .06 .7 1.77 scribed in our copending US. patent application Ser. Nos. 243,463 and 244,276, Example 32 was repeated 0 173 137 232 and in addition to measurement of the photographic 11-075 219 properties of the emulsions immediately after their 24 0.25 0.07 1.68 1.80 2.17

Q um L62 178 221 preparation, samples were sub ected to advanced aging 1.45 1.94 2.07 by incubation for 7 days at F and 60% relative hu- 0.025 0.07 1.74 1.70 2.00 0W5 006 L72 1.80 216 35 midlty. The results are shown in the following Tables 18 0.25 0.05 1.73 1.92 2.25 XI and XII.

Table XI Compound added Quantity Initial properties After incubation Example added Rela- Aver- Rel a- Aver- No. (mM/M) tive age tive age log conlog confog speed trast Dmax Fog speed trast Dmax No addition 0.10 1.55 1.78 2.15 0.04 1.48 0.99 1.47 Azodi carbon 0.625 0.04 1.56 1.59 1.91 0.03 1.41 1.055 1.45

amide Table XII Compound addcd Quantity Initial properties After incubation (Example added Rcla- Aver- Reia- Aver- No.) (mM/M) tive age tivc age logconlog con- Fog speed trast Dmax Fog speed trust Dmax Nu addi- 0.15 1.67 1.54 1.13 0.24 1.69 1.09 1.70

tion Azodicurhon- 0.625 0.06 1.65 1.52 1.96 0.07 1.69 1.19 1.63

amide Table X11 --Continued Initial properties After incubation Example added Rela- Aver- Rcla- Aver- No.) (mM/M) tive age tive age logconlog con Fog speed trast Dmax Fog speed trast Dmax As can be seen from these results, the azocarbonamides which had quaternary ammonium substituents strongly desensitized the emulsion initially and also kept the fog at a low level, but then decomposed during incubation so that the light sensitivity of the emulsions returned while the fog was still kept at very low levels. These compounds are therefore suitable oxidizing agents for use as described in our copending US. patent application Ser. Nos. 243,463 and 244,276.

I claim:

1. A silver halide photographic emulsion which has in fog inhibiting reactive association therewith at least a fog inhibiting amount of an azocarbonamide having one azo-carbonamide group.

2. The emulsion of claim 1 which has in fog inhibiting reactive association therewith an azocarbonamide of the formula wherein Ar is an aromatic group and R is a carbonamide.

3. The emulsion of claim 2 wherein the azocarbonamide has an oxidation potential of 0.08 to +0.50.

4. The emulsion of claim 2 wherein the azocarbonamide is hydrolytically unstable.

5. The meulsion of claim 2 wherein a substituent on the nitrogen atom of the carbonamide group of the azocarbonamide contains at least one quaternary ammonium, group.

6. The emulsion of claim 5 wherein the azocarbonamide has the formula wherein Ar is an aromatic group and R is a carbonamide.

9. The emulsion of claim 1 wherein the azocarbonamide is present in an amount of at least 0.025 millimoles per mole of silver.

10. The element of claim 8 wherein the azocarbonamide is present in an amount of at least 0.025 millimoles per moles of silver.

UNITED STATES PA'IEN'I OFFICE CER'IIFICA'FE ()F CORRECTION PAH 1 N0. 5 900 3 BATH) Aupgustl), 197?) INVlNTURQ') Alan N. Ferg on H is celtlhcd that crrm appears in lhv nb0vu--ident1ti0d patent and that said LLHCIS Patent :uc hcluhy collected as shown below:

(30.1.. 2 Line (5 under "1) max" in Table XII 1.13 should be Col. 25, 1.1110 Mi, Claim 5, meulsion" should be -emulsion--.

Signed and Scaledthis eleventh 0* November 19 75 [SEAL] Anesr: 

1. A SILVER HALIDE PHOTOGRAPHIC EMULSION WHICH HAS IN FOG INHIBITING REACTIVE ASSOCIATION THEREWITH AT LEAST A FOG INHIBITING AMOUNT OF AN AZOCARBONAMIDE HAVING ONE AZO-CARBONAMIDE GROUP.
 2. The emulsion of claim 1 which has in fog inhibiting reactive association therewith an azocarbonamide of the formula Ar - N N - R wherein Ar is an aromatic group and R is a carbonamide.
 3. The emulsion of claim 2 wherein the azocarbonamide has an oxidation potential of -0.08 to +0.50.
 4. The emulsion of claim 2 wherein the azocarbonamide is hydrolytically unstable.
 5. The meulsion of claim 2 wherein a substituent on the nitrogen atom of the carbonamide group of the azocarbonamide contains at least one quaternary ammonium, group.
 6. The emulsion of claim 5 wherein the azocarbonamide has the formula (Ar - N N - R) X wherein X represents one or more negatively charged ions sufficient to give the azocarbonamide electrical neutrality.
 7. The emulsion of claim 2 wherein the aromatic group of the azocarbonamide is a phenyl or a naphthyl group.
 8. Photographic element comprising a silver halide photographic emulsion which contains therein or in a layer adjacent thereto a fog inhibiting amount of an azocarbonamide of the formula: Ar - N N - R wherein Ar is an aromatic group and R is a carbonamide.
 9. The emulsion of claim 1 wherein the azocarbonamide is present in an amount of at least 0.025 millimoles per mole of silver.
 10. The element of claim 8 wherein the azocarbonamide is present in an amount of at least 0.025 millimoles per moles of silver. 